Laser profilometry (LP) is explored as a means for mapping and quantifying the corrosion damage of AA7075-T6 (UNS A97075) specimens exposed to cyclic prohesion spray for various times. Analysis tools were developed and used to provide quantitative measurements of the distribution of damage site shape, area and volume, and depth. Evolution of these parameters with exposure time was examined. The measured maximum damage site depths of 22 μm to 55 μm agree well with values obtained using other techniques. Modeling the damage sites as elliptical surface flaws yielded maximum ∆K values for the individual fatigue specimens (2 MPa√m to 5 MPa√m) that are equal to or higher than typical fatigue crack growth thresholds available in the literature. The maximum (or average) ∆K values calculated from the corrosion damage distributions correlate well with measured fatigue life.

Subject
Pits, Corrosion fatigue, Prohesion, Metallography, Stress, Flaws, Corrosion modeling, Contours, Lasers, Pitting, Fatigue, Damage, Types of corrosion
Keywords:
AA7075, aging aircraft, aluminum, elliptical crack, endurance limit, fatigue life, morphological phenomena, pit morphology, pitting corrosion, structural integrity
NACE International
2003
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